Diazo-type copying

ABSTRACT

Diazo-type reproduction wherein a 3-H-indoline color-coupling compound is transferred from a transfer sheet material carrying the same by means of heat to a receiving material carrying a diazonium compound for imagewise reaction therewith to produce a azo dye image. The heat can be applied to the transfer material directly in the form of an image or the diazonium carrying receiving material can be preliminarily exposed to light imagewise to decompose the diazonium compound in the exposed areas with heat being uniformly applied to the transfer material to transfer the coupling compound for reaction with residual undecomposed diazonium compound. Heat in the temperature range of 80-140* C. can be used with these specific coupling compounds and the coupling can take place under acid as well as alkaline conditions.

United States Patent Inventors Albert Lucien Poot Kontich; Rene Alols van Brandt, Kessel, both of Belgium Appl. No. 790,150 Filed Jan. 9, 1969 Patented Nov. 16, 1971 Assignee Gevaert-Agfa N.V.

Mortsel, Belgium Priority Jan. 9, 1968 Great Britain 1,320/68 DIAZO-TYPE COPYING 9 Claims, No Drawings U.S. Cl

Field of Search References Cited UNITED STATES PATENTS 2,815,338 12/1957 Reugg 260/326.l1X

3,076,707 2/1963 Lawton et a1. 96/49 X 3,392,020 7/1968 Yutzy et a1. 250/65.1 X

3.318,699 5/1969 Lind 96/49 FOREIGN PATENTS 1 123,399 6/1956 France 96/49 907,724 10/ 1962 Great Britain 96/49 Primary Examiner-Norman G. Torchin Assistant Examiner-Charles L. Bowers, Jr. Attorney-William .1. Daniel ABSTRACT: Diazo-type reproduction wherein a S-H-indoline color-coupling compound is transferred from a transfer sheet material carrying the same by means of heat to a receiving material carrying a diazonium compound for imagewise reaction therewith to produce a azo dye image. The heat can be applied to the transfer material directly in the form of an image or the diazonium carrying receiving material can be preliminarily exposed to light imagewise to decompose the diazonium compound in the exposed areas with heat being uniformly applied to the transfer material to transfer the coupling compound for reaction with residual undecomposed diazonium compound. Heat in the temperature range of 80-140 C. can be used with these specific coupling compounds and the coupling can take place under acid as well as alkaline conditions.

DIAZO-TYPE COPYING The present invention relates to compounds, materials and processes for recording and reproducing information. More particularly the present invention is concerned with diazotype copying.

A number of diazo-type processes is known from which one of the more recently developed is described and claimed in the U.S. Pat. Spec. No. 2,789,904 of Charles H. Benbrook and Clifford E. l-lerreck issued Apr. 23, 1957. in such a process a diazonium compound in a sheet material is exposed and afterwards contacted with a sheet material impregnated with a coupler capable of thermal transfer. The coupler may be selected from the group consisting of phenols, naphthols and compounds containing a reactive methylene group but being free of primary amino groups.

According to the said patent specification the thermal transfer takes place at temperatures between 140 and 225 C. At these temperatures, the layers containing the light-sensitive diazocompounds can be developed within a fraction of a minute in the absence of ammonia, dilute alkali or volatile amines.

There has now been found a class of couplers suited for use in diazo-type printing and containing a reactive methylene group, which enables the above described process to be carried out at a temperature in the range of 70 to 140 C., and whose reactivity is so high that the coupling can be performed in acid as well as in alkaline medium.

The said class of compounds is represented by the following general formula:

CH; on

/:CH2 N wherein:

Z represents the necessary atoms to close an aromatic ring or aromatic ring system including a substituted aromatic ring or aromatic ring system, e.g. a benzene nucleus, a naphthalene nucleus or a substituted benzene nucleus, e.g. a benzene nucleus substituted with a C -C alkyl group, a phenyl group, an acetyl group, a nitro group, a cyano group, a hydroxyl group or an acetoxy group, and

R represents an aliphatic group including a saturated, un-

saturated, cycloaliphatic and substituted aliphatic group such as an alkyl group, e.g. a C C alkyl group, a cyclohexyl group, a cyclopentyl group, an allyl group, a substituted alkyl, e.g. an alkyl group substituted with a phenyl group or a hydroxy group, or an aromatic group, e.g. a phenyl group.

Light-sensitive diazonium compounds suited for the coupling with the above active methylene compounds may be of the low as well as of the high-reactivity type, so diazonium compounds used in a common wet as well as those used in a common dry diazo-type process are considered.

it is preferred to employ as the diazocompound one of the commonly used stabilized diazonium salts, preferably the zinc chloride double salt. Other stabilized derivatives may be used too, e.g. the fluoborates and oxalates.

Exemplary diazocompounds are the diazonium salts obtained by diazotization of the following amines:

p-amino-N,N-dimethylaniline p-amino-N,N-diethylaniline p-amino-N-ethyl-N-B-hydroxyethylaniline p-amino-N-ethyl-N-benzylaniline p-amino-phenylmorpholine p-amino-(2,5-diethoxy)-N-benzoylaniline p-amino-( 2,5-dibutoxy )-N-benzylaniline 4-amino-(2,5-dimethoxy)-4'-methyldiphenyl sulfide p-amino-o-ethoxy-N,N-diethylaniline p-amino-o chloro-N,N-diethylaniline.

As suitable supports or carriers for the diazonium salts or compositions containing them are mentioned absorbent material, e.g. grained aluminum, ordinary wood pulp paper or rag-type paper but also textiles including fabrics made from cotton, cellulose acetate, regenerated cellulose, in other words all types of woven or felted materials that can be impregnated with a solution containing a diazonium compound or mixture of diazonium compounds. For preparing transparent diazocopies preferably transparent resin supports (e.g. a polyester resin sheet) are used to which the diazonium salt is applied in a hydrophilic binder, e.g. in gelatin.

The coating composition for applying the diazonium compounds may contain a substance increasing the storage stability, e.g., an acid such as citric acid, tartaric acid, boric acid, sulfosalicyclic acid, phosphoric acid, trichloroacetic acid, tribromoacetic acid or l,3,5 -naphthalene trisulfonic acid in an amount of l to 10 percent by weight in respect of the diazonium salt. The coating may further contain antioxidizing agents improving the whiteness of the areas wherein the diazonium compound has been destroyed. As suitable antioxidants may be mentioned urea, thiourea, ascorbic acid and allyl isothiocyanate in concentrations ranging from 25 to 15 percent by weight in respect of the diazonium salt.

Thermally transferable couplers are preferably incorporated into a material (hereinafter called "transfer material") with absorbent nature or porous character. As absorbent materials for carrying the thermally transferable substance are particularly mentioned cloth, felt, paper, e.g. blotting paper, foamed rubber, sponge porous stone, porous porcelain and sintered glass.

The thermal transfer can be realized by distilling the coupler from the transfer material to the receiving sheet or layer containing the diazonium compound, which sheet or layer hereinafter is called receiving material. According to another embodiment, the coupler is transferred in liquid or dissolved state, in the latter case with the aid ofa noncoupling liquid substance or substance being transformed in liquid state during heating.

The coupler may also be applied as a dry powder (toner) either or not mixed with carrier particles.

According to a further embodiment, the coupler can be transferred to the receiving material by means of a substance or substances applied in layer form, which substance(s).in heated state stick(s) to the receiving material, e.g. a thermoplastic polymer or colloid, e.g. a polyoxyalkylene compound, poly-N-vinylpyrrolidone, gelatin, animal glue, a watersoluble melamine resin or thermoplastic latex polymer.

Preferred active methylene compounds which can thermally be transferred without the aid of an auxiliary substance, i.e., can be volatilized or sublimed in the temperature range of 8 to C., are listed hereinafter:

1,3 ,3-trimethyl-2-methylene-indoline l-hydroxyethyl-3 ,3-dimethyl-2methylene-indoline l-hydroxypropyl- 3 ,3-dimethyl-2-m ethylene-indoline l-hydroxybutyl-3,3-dimethyl-2-methylene-indoline l-n-hexadecyl-3,3-dimethyl-2-methylene-indoline l.3,3-trimethyl-5-hydroxy-Z-methylene-indoline l,3,3-trimethyl-6-hydroxy-2-methylene-indoline l ,3,3-trimethyl-5-nitrO-Z-methylene-indoline The indoline compounds used according to the present invention are prepared by starting from the corresponding 3-H- indolium salts. The following general preparation method illustrates their production.

One mole of a S-H-indolium compound corresponding to the following general formula:

wherein Z and R have the same meaning as described above and X represents an anion,

is dissolved in l.5 liter of water. To the obtained solution 0.5 liter of concentrated ammonia is added at room temperature while stirring. An oily product forms. The mixture is heated at 5060 C. and thereupon slowly cooled till room temperature while stirring.

The methylene base is extracted with ether and the extract dried on anhydrous sodium sulfate The ether is removed by evaporation and the methylene base is further purified by vacuum distillation or recrystallization.

The preparation of the 3-H-indolium compounds is described in the U.S. Pat. application Ser. No. 790,148.

Solvents that can be used for applying the coupler to the transfer material are, e.g., alcohols and ketones having a boiling point lower than 100 C. In order to speed up transfer and coupling, the couplers are used in combination with humectants. Suitable humectants for the active methylene compounds of the general formula, which play a part in the thermal transfer of the said compounds, are found in the class of polyols, e.g., diethylene glycol, glycerol, and hexitols such as sorbitol. Surfactants of the nonionic type, e.g. polyoxyalkylene glycols such as polyethylene glycols having an average molecular weight from 2,000 to 6,000, are also of interest for speeding up the transfer and coupling reactions. In general the weight of humectant, solvent or surfactant in the transfer material is not higher than 200 percent by weight in respect of the coupler.

When using without additive 5 g. of an above mentioned reactive methylene compound applied from an acetone solution per sq.m. of common document paper, sufficiently dense copies can be produced by thermal transfer in the temperature range of 70 to 140 C.

The way, however, of applying the coupler to the exposed receiving material is not necessarily restricted to dry or semidry transfer systems. The coupler may be applied as has already been said in dissolved or finely dispersed state from a liquid. On applying that technique, however, as less liquid as possible should be used in order to produce touch-dry copies. For that purpose the solution or dispersion is applied by spraying, by means of a lickroller, or a porous or absorbent material, eg a felted or woven material impregnated with a solution of the coupler. By a heating after treatment, e.g. by contact with a hot roller or irradiation with infrared light, surplus liquid can be removed. An absorbing or porous carrier impregnated with the coupler can be reused for making several prints.

The heat necessary for a thermally nondifferential transfer of coupler to the receiving material can be supplied by a hot roller as is used, e.g., in a Dry Silver Process equipment manufactured by Minnesota Mining and Manufacturing Company, St. Paul, Minn., U.S.A., or by nondifferential infrared expo sure. In the latter case the transfer material should preferably contain (a) finely divided infrared-absorbing substance(s) transforming absorbed infrared light into heat. Said substance(s) can also make part of an auxiliary sheet held in intimate heat-conductive contact with the sheet material containing the active methylene compound.

Heating techniques based on the use of infrared and visible light-absorbing substances are described in the Canadian Pat. No. 787,843 filed Dec. 4, 1964 by Gevaert Photo-Producten NV. and the Belgian Pat. No. 681,138 filed May 17, 1966 by Gevaert-Agfa.

Although a diazo-type copy is commonly prepared by imagewise exposing a sheet containing a diazonium salt to UV. radiation and coupling the nonexposed diazonium salt with a coupler nondifferentially applied thereto or contained therein, it is also possible to produce an azo dye image by imagewise transferring a coupler to a nonexposed sheet containing a diazonium salt Said imagewise transfer can be realized by imagewise heating a transfer material containing the heat-transferable coupler. According to one embodiment, imagewise heating proceeds by the accumulation of heat in the image markings of an original as is done in classical thermography.'For that purpose the coupler is preferably coated onto a thin heat-conductive sheet, e.g. a paper sheet, or incorporated therein by 5 impregnation. During exposure to infrared radiation the sheet containing the diazonium salt is held in contract with the coupler-releasing side of the transfer sheet while the other side stands in heat-conductive relationship with the infrared absorbing image markings of the original. During exposure the 0 heat produced in said imagemarkings is conducted to the coupler, which as a' consequence thereof is imagewise and thermally transferred so as to form an azo-dye image on the receiving sheet.

According to another embodiment imagewise heating can proceed by imagewise irradiating a sheet material containing colored oxides, sulfides or carbonates of heavy metals, particularly of those heavy metals having an atomic weight between 45 and 210, such as manganese or lead sulfide, or these heavy metals themselves in finely divided state such as silver, bismuth, lead, iron, cobalt or nickel. Carbon black being an excellent heat-generating product when irradiated with infrared and/or visible light is preferably used.

The powdery substances absorbing infrared and/or visible light have a grain size preferably lower than 0. l

In the recording material considered above the light-absorbing substance (visible and/or infrared light-absorbing) is distributed all over the transfer layer, e.g., is dissolved or dispersed in a binder for the coupler or in the paper mass of a paper sheet.

According to a particular process for imagewise transferring a coupler by heat, a pattern of radiation-absorbing substances conform to the image to be reproduced is formed in the transfer sheet. Such a pattern can be obtained by starting from a light-sensitive substance or composition which on exposure forms an infrared-absorbing substance converting absorbed light into heat. If required by the nature of the light-sensitive substance or composition, the exposure may be followed by a suitable development.

Preferably light-sensitive silver halide is used as the substance from which infrared-absorbing silver can be formed imagewise. A silver halide emulsion applied in the present invention may be of the negative as well as of the positive type. The silver halide is preferably combined with a suitable developing agent, e. g. hydroquinone, so that the development may be carried out with a so-called activating bath, which is an alkaline aqueous solution containing no developing agent.

An alternative way of bringing about an informationwise distribution of infrared-absorbing substance in the recording material is to form a silver image in situ from complexed silver halide introduced into the recording material and deriving from unexposed portions of an informationwise exposed silver halide emulsion layer as known per se in silver salt diffusion transfer process.

When the coupler is used in heat-conductive relationship with an imagewise distributed infrared-absorbing substance,

the transfer of the coupler can proceed by a nondifferential exposure of the transfer material to infrared radiation. Suitable radiation sources emitting infrared light are commercially available. The heat-generating exposure of a silver image can also be effected by visible light, which is preferably of high in- Example A transfer paper (A) and a light-sensitive paper (B) were prepared as follows:

A. l0 g. of an active methylene indoline of the list in the description were dissolved in 200 cc of acetone and coated on a document paper at a rate of 100 cc. per sq.m.

B. g. of a diazonium compound corresponding with one of the amines particularly described were dissolved in 1,000 cc. of water and coated on a document paper at a rate of 100 cc. per sq.m.

The light-sensitive material (B) was exposed for 10 sec. to U.V. radiation through a positive silver image transparency by means of an ultraviolet high-pressure mercury vapor bulb of 80 w. placed at a distance of cm.

The exposed paper was heated in contact with material (A) in a thermographic copying apparatus with a heating roller whose temperature was maintained between 8 and 100 C. On the material (B) a visible image was formed.

The material (A) could be used 10 times before it became necessary to apply a fresh amount of active methylene compound.

What we claim is:

I. In a process of diazo-type reproduction wherein transfer sheet material carrying a heat-transferable azo coupling compound is contacted with a receiving sheet material carrying a diazonium compound and heat is applied to said first material to cause transfer of said coupling compound in at least an image-shaped pattern, said transferring coupling compound reacting with said diazonium compound to produce an azo dye image, the improvement wherein said coupling compound is an active methylene compound according to the following general formula:

R wherein 2 represents the necessary atoms to close a benzene ring system, and

R represents a lower alkyl or hydroxyalkyl group 2. A process according to claim 1, wherein the said coupling compound is imagewise transferred to said material containing said diazonium compound by means of heat applied in an image pattern to said transfer material to cause azo dye formation in areas of the receiving sheet contiguous to the image pattern of said transfer material.

3. A process according to claim 1, wherein the receiving material containing the diazonium compound is imagewise exposed to ultraviolet radiation in order to imagewise destroy the diazonium compound and heat is applied uniformly to said transfer material to cause azo dye formation in unexposed areas of the receiving sheet.

4. A process according to claim 2, wherein the active methylene compound is one that can be volatilized or sublimed in the temperature range of to C. and said transfer material is heated to a temperature in said range.

5. A process according to claim 4, wherein the active methylene compound is one of the following group:

1,3 ,3-trimethyl-2-methylene-indoline l-hydroxyethyl-3,3-dimethyl-Z-methyIene-indoline l-hydroxypropyl-3,3-dimethyl-2-methylene-indoline l -hydroxybutyl3,3-dimethyl-2-methylene-indoline l-n-hexadecyl-3,3-dimethyl-2-methylene-indoline 1,3 ,3-trimethyl-S-hydroxy-Z-methylene-indoline 1,3 ,3-trimethyl-6-hydroxy-2-methylene-indoline 1 ,3,3-trimethyl-5-nitro-2-methylene-indoline.

6. A process according to claim 1, wherein said coupling compound is contained in a thermoadhesive layer.

7. A process according to claim 2, wherein the imagewise heating is effected by heat conducted from infrared-absorbing image marks of an original to the transfer material containing the coupling compound.

8. A process according to claim 2, wherein the imagewise heating is effected by imagewise exposing the transfer material containing the active methylene compound to infrared and/or visible light, which is absorbed and converted into heat in substances nondifferentially distributed in said transfer material or making part of an auxiliary sheet material being in heatconductive contact with the transfer material.

9. The process of claim 1 wherein said coupling reaction takes place in the absence of alkali.

UNETED STATES ?ATENT @FFECE CERTIFiCATE G CQEERECTEON Patent N 3 ,620 .741 Dated November 16, 1971 lnventofls) Albert Lucien POOT et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, claim 1, correct the formula as follows.-

n C CH3 Z =CH7 N Signed and sealed this 232% day of May EDWIARD L LFLE'ICHER, JR. attesting Officer DRM PC4050 USCOMM-DC scam-ps9 U 5v GOVERNMENT PRlhTlNG OFFICE 1969 0-326 334 

2. A process according to claim 1, wherein the said coupling compound is imagewise transferred to said material containing said diazonium compound by means of heat applied in an image pattern to said transfer material to cause azo dye formation in areas of the receiving sheet contiguous to the image pattern of said transfer material.
 3. A process according to claim 1, wherein the receiving material containing the diazonium compound is imagewise exposed to ultraviolet radiation in order to imagewise destroy the diazonium compound and heat is applied uniformly to said transfer materiAl to cause azo dye formation in unexposed areas of the receiving sheet.
 4. A process according to claim 2, wherein the active methylene compound is one that can be volatilized or sublimed in the temperature range of 80* to 140* C. and said transfer material is heated to a temperature in said range.
 5. A process according to claim 4, wherein the active methylene compound is one of the following group: 1,3,3-trimethyl-2-methylene-indoline 1-hydroxyethyl-3,3-dimethyl-2-methylene-indoline 1-hydroxypropyl-3,3-dimethyl-2-methylene-indoline 1-hydroxybutyl-3,3-dimethyl-2-methylene-indoline 1-n-hexadecyl-3,3-dimethyl-2-methylene-indoline 1,3,3-trimethyl-5-hydroxy-2-methylene-indoline 1,3,3-trimethyl-6-hydroxy-2-methylene-indoline 1,3,3-trimethyl-5-nitro-2-methylene-indoline.
 6. A process according to claim 1, wherein said coupling compound is contained in a thermoadhesive layer.
 7. A process according to claim 2, wherein the imagewise heating is effected by heat conducted from infrared-absorbing image marks of an original to the transfer material containing the coupling compound.
 8. A process according to claim 2, wherein the imagewise heating is effected by imagewise exposing the transfer material containing the active methylene compound to infrared and/or visible light, which is absorbed and converted into heat in substances nondifferentially distributed in said transfer material or making part of an auxiliary sheet material being in heat-conductive contact with the transfer material.
 9. The process of claim 1 wherein said coupling reaction takes place in the absence of alkali. 